The significance of Mitosis are :-
1. It is an equational division through which identical daughter cells are produced having the same amount and type of genetic constitution as that of the parent cell.
2. It is responsible for growth and development of multi-cellular organisms from a single-celled zygote.
3. The number of chromosomes remains the same in all the cells produced by this division. Thus, the daughter cells retain the same characters as those of the parent cell.
4. It helps the cell in maintaining proper size.
5. Mitosis helps in restoring wear and tear in body tissues, replacement of damaged or lost part, healing of wounds and regeneration of detached parts (as in tail of a lizards).
6. It is a method of multiplication in unicellular organisms.
7. If mitosis remains unchecked, it may result in uncontrolled growth of cells leading to cancer or tumour.
The significance of meiosis :-
1. It maintains the same chromosome n umber in the sexually reproducing organisms. From a diploid cell, haploid gametes are produced which in turn fuse to form a diploid cell.
2. It restricts the multiplication of chromosome number and maintains the stability of the species.
3. Maternal and paternal genes get exchanged during crossing over. It results in variations among the offspring.
4. All the four chromatids of a homologous pair of chromosomes segregate and go over separately to four different daughter cells. This leads to variation in the daughter cells genetically.
Following are the differences between Mitosis and Meiosis:
|1||Type of Reproduction||Asexual||Sexual|
|3||Crossing Over||No, crossing over cannot occur.||Yes, mixing of chromosomes can occur.|
|4||Number of Divisions||One||Two|
|5||Pairing of Homologs||No||Yes|
|6||Mother Cells||Can be either haploid or diploid||Always diploid|
|7||Number of Daughter Cells produced||2 diploid cells||4 haploid cells|
|8||Chromosome Number||Remains the same.||Reduced by half.|
|9||Chromosomes Pairing||Does Not Occur||Takes place during zygotene of prophase I and continue upto metaphase I.|
|10||Creates||Makes everything other than sex cells.||Sex cells only: female egg cells or male sperm cells.|
|11||Takes Place in||Somatic Cells||Germ Cells|
|12||Chiasmata||Absent||Observed during prophase I and metaphase I.|
|13||Spindle Fibres||Disappear completely in telophase.||Do not disappear completely in telophase I.|
|14||Nucleoli||Reappear at telophase||Do not reappear at telophase I.|
|15||Steps||Prophase, Metaphase, Anaphase, Telophase.||(Meiosis 1) Prophase I, Metaphase I, Anaphase I, Telophase I; (Meiosis 2) Prophase II, Metaphase II, Anaphase II and Telophase II.|
|16||Karyokinesis||Occurs in Interphase.||Occurs in Interphase I.|
|17||Cytokinesis||Occurs in Telophase.||Occurs in Telophase I and in Telophase II.|
|18||Centromeres Split||The centromeres split during anaphase.||The centromeres do not separate during anaphase I, but during anaphase II.|
|20||Prophase||Duration of prophase is short, usually of few hours.||Prophase is comparatively longer and may take days.|
|21||Synapsis||No Synapsis||Synapsis of Homologous chromosomes takes place during prophase.|
|22||Exchange of Segments||Two chromatids of a chromosome do not exchange segments during prophase.||Chromatids of two homologous chromosome exchange segments during crossing over.|
|23||Discovered by||Walther Flemming||Oscar Hertwig|
|24||Function||Cellular reproduction and general growth and repair of the body.||Genetic diversity through sexual reproduction.|
|25||Function||Takes part in healing and repair.||Takes part in the formation of gametes and maintenance of chromosome number.|
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